Optical control of sunlight at window openings with a directionally selective,transparent sunshade to eliminate glaring sunlight rays while providing normal daylight illumination at windows



Oct. 7, 1969 B. I. SEEGER 3,471,221

OPTICAL CONTROL OF SUNLIGHT AT WINDOW OPENINGS WITH A DIRECTIONALLYSELECTIVE, TRANSPARENT SUNSHADE TO ELIMINATE GLARING SUNLIGHT RAYS WHILEPROVIDING NORMAL DAYLIGHT ILLUMINATION AT wmnows Filed 0ct.'2 l. 1965ELYTLR BERNARD 1. 555619,?

6&3. BY v A TTOAPA/E V United States Patent US. Cl. 350-263 3 ClaimsABSTRACT OF THE DISCLOSURE At building openings and elsewhere whereglaring sunlight control is needed, multiple prism slats made oftransparent material are rotatively positioned adjacent one another as ablind, and the slats are moved as the sun moves to intercept glare raysfrom the sun as respective sunlight glare rays enter respective thinwedge transport slats to be internally trapped through progressing slatinterior deflections, as nonglare sunlight rays illuminate the spacebeyond the transparent blind.

This invention relates to transparent material assemblies used to arrestdirect sun glare and heat, while affording minimal interference withdaylight illumination and outward visibility in other directons. Moreparticularly in the illustrated embodiment, such an assembly comprisestransparent materials arranged as horizontal slats of a conventionalvenetian blind, although the slat arrangement may alternatively bevertical.

The purpose of the invention is to control sunlight and its glareeffects with transparent material assemblies which at all times continueto pass sufiicient quantities of indirect daylight for continued activeuse of space beyond any slat assembly without having to resort toartificial lighting.

The invention, briefly described in reference to an illustratedembodiment comprises horizontal blind arrangements of multiple slatswhich are collectively moved and positioned to intercept as many aspossible of the glare rays from the sun, with each slat being a thinwedge and preferably having its thick edge V-grooved with all surfacesbeing smooth.

The invention is illustrated in the accompanying drawings, whereinFIGURE 1 is a perspective partial sectional view of a window in a homeor office with a horizontal blind of transparent material arranged in aworking position;

FIGURE 2 is an enlarged end view of the transparent material made into athin wedge slat, showing in dotted lines a typical optical path of anaccepted and desirable nonglare light ray; and

FIGURE 3 is an enlarged end view of the transparent material similar toFIGURE 2, showing in dotted lines the optical path of a glaring sunlightray internally trapped and dissipated through successive totalreflections.

Referring to FIGURE 1, the illustrated embodiment of this inventionprovides horizontal blinds 12 of transparent materials 14 to opticallycontrol sunlight at window or like openings 16. The materials used arehighly transparent to all visible light. However, these materials aregenerally shaped as indicated in FIGURES 2 and 3 to trap the glaring sunrays and their heat energy.

In reference to the utilization of a transparent polymethyl methacrylatematerial, having a refractive index ice of 1.49, a preferredconstruction of a slat 22 is shown in FIGURES 2 and 3. A thin wedgeshape is used with a loading pointed edge 24 nearest the opening 16having an apex angle which determines the size of the following slowlywidening transparent body which terminates in a thicker edge 26 that isV-grooved 28. All the surfaces of the thin wedge slat 22 are smooththroughout its length which is determined by the width of the opening16, The optimum apex angle of these transparent slats depends upon therefractive index of the slat material, as well as upon stowageconsiderations in retracting the blind from its functional deployment.

The multiple arrangement of these slats 22 may be undertaken by some ofthe ways already known where they are preferably held and rotated byslat end mounting devices, not shown. The slat suspension andpositioning controls, not shown, will maintain a common attitude of allslats 22 to trap the glare rays which may be coming directly from thesun, reflected from a water surface, glass surface of an adjacentbuilding, etc.

The successful control of sunlight or other glare rays of extremeintensity and the simultaneous passage of less intense and indirectlight is illustrated in FIGURES 2 and 3. The slat 22, enlarged overFIGURE 1, as shown in FIGURE 2 is receivinga less intense light ray Bwhich it passes to provide diffused daylight lighting in an interiorspace. In FIGURE 3, however, slat 22 is receiving an intense direct sunray A which it traps during several interior total deflections. Suchentrapment is made even more effective by the presence of the V-groove28 in its edge 26.

It will be realized that what has been separately illustrated in FIGURES2 and 3, is actually occurring simultaneously as light rays pass intoeach slat 22 of the blind 12 to be selectively optically directed toachieve the purpose of the invention to provide daylight illuminationand outward visibility without glare. During this selective opticaldirection of blind 12, the wedge points 24 of slats 22 are directed ator nor the position of the sun in operation of the blind.

I claim:

1. A transparent material assembly to optically control sunlight and itsglare effects while providing outward visibility and continuing to passsuflicient quantities of daylight for continued active use of spacebeyond such transparent material assembly without having to resort toartificial lighting, comprising:

(a) conventional positioning devices adapted to hold and to pivotmultiple prism slats of transparent material across an area at whichglare rays of sunlight may be incident; and

(b) multiple prism slats, each of which is thin wedge shaped in crosssection with its pointed edge oriented toward the direction of the sun,are fitted in part into the conventional positioning devices, foradjustment to prevent passage of glare rays of sunlight through thesunlight area.

2. A transparent material assembly to optically control sunlight, asclaimed in claim 1, wherein each prism slat of wedge shape has itslarger end recessed to further confine internally reflected light rays.

3. A transparent material assembly adapted for use at an opening in astructure to optically intercept glare effects of direct sunlight, whilepassing a sufficient level of diffused daylight to avoid recourse toartificial lighting, comprising:

(a) multiple parallel transparent prism slats, each of which is thinwedge shaped in cross section with its pointed edge oriented toward thedirection of the 3 4 sun, to arrest visible and invisible solarradiations R f C1 d within a range of incidence angles that isrelatively e erences e narrow, but broad enough to substantially exceedthe UNITED STATES ATENTS angular subtense of the sun, and to passdesirable 719,065 1/1903 Wadsworth 350 263 and beneficial daylightwithin broad ranges of in- 5 1,937,342 11/1933 Higbie 350 263 cidenceangles that are symmetrically disposed on either side of the narrowerarresting range of visible FOREIGN PATENTS and invisible solarradiations; and 336,556 3/1904 France.

(b) conventional positioning devices adapted to hold and to pivot themultiple parallel transparent prism 10 JULIA E. COINER, Primary Examinerslats across an opening in a structure to keep them directionallyselective to arrest the visible and in- US. Cl. X.R. visible solarradiations thereby eliminating the glare 350-465 while passing dilfuseddaylight.

